At one local bus stop you won’t need to check your watch to see if your bus is coming soon — just take a look at student Michael Yamamoto’s sundial. When the Seattle sun is actually shining, that is.

Yamamoto designed the dial this spring in an honors seminar course with Astronomy Professor Woodruff “Woody” Sullivan called Special Topics: Sundials and Timekeeping. Sullivan said the class produced several sundial ideas that were nice, but that Yamamoto’s really stood out.

“It’s a beautiful concept,” Sullivan said. “I don’t know of anyone who’s done something like this. If you think about it, all you need to know is when the next bus is coming, you don’t need to know the time.”

Metro bus number 68, southbound on 25th Ave. NE near University Village, runs every half hour. So if the sun’s shadow is about halfway between two points marked by Yamamoto on his dial, you know you have about 15 minutes to wait.

Yamamoto, a computer science and chemistry major, happened on the idea while searching for “places where telling time is useful, but a timepiece did not already exist,” he wrote in an e-mail.

His own experience with a bus got him started. “After hearing the details of our final project in class, I went to take the bus back to the apartment and realized I had left my watch at home. I wasn’t sure if the bus had come yet, and it was late so no one else was at the stop to ask. Unsure if the bus had come, I ended up walking back, only to see the bus pass me a few minutes later. As the bus passed, I realized that it would have been great if there were some sort of time piece at the bus stop so I would have known, and the idea blossomed from there.”

Sure, it’s a bit of a Rube Goldberg way of divining the time. It’s light-hearted, but not really frivolous, Sullivan said. And he noted that, really, it’s a little more complicated than a shadow pointing to a mark. “A sundial normally reads solar time, which is different from clock time, but Michael’s design cleverly actually reads clock time.”

Sullivan said his work in 1994 creating the big sundial at the Physics-Astronomy building made a “sundial nut” out of him. He added, “I’m out to make Seattle the sundial capital of North America, and we’re well on our way.”

Sullivan’s enthusiasm for the subject is contagious, Yamamoto said. “It was great discovering the many forms which the simple dial can take beyond the stereotypical horizontal dial,” he wrote, “and Professor Sullivan’s experience working on a sundial for the Mars Rover was truly unique.”

It’s all being done in a bit of a guerilla fashion — Sullivan said Yamamoto called Metro, Seattle’s bus authority, to discuss the sundial but “could never find the right person.”

So, he said, “We’ve just gone ahead and put it up. To me it’s an interesting sociological quesiton as to how long it will last.”